“The skies were star-spangled and blue phosphorescence would spray like diamonds in the sea … the sand glowed silver and the waves danced alive as they hit the shore.” The year is 1988 and the now legendary full-moon party has hit the tropical Thai island of Koh Phangan for the first time, described to TIME by intrepid Scotsman Colin Hinshelwood, who bobbed over on a fishing boat from neighboring Koh Samui. Hippies from across the globe used to quietly gather at this idyllic enclave, drifting in on clouds of marijuana smoke to sit on a beach, strum a battered guitar and simply be. Today, however, the only blue spray you’ll see might be the lurid curaçao cocktail expelled from the guts of a retching 20-something. This onetime Eden has degenerated into a modern-day Gomorrah awash in tawdry techno, cheap fast food and wasted millennials.

Every month of the year, thousands of revelers make the pilgrimage to this isle of indulgence. Haad Rin beach, on Koh Phangan’s southern tip, is a one-mile strip onto which 30,000 people, mostly young foreigners, will cram themselves on busy nights. The sand fills with makeshift stalls selling buckets — literally the kind of plastic pails children take to the beach — brimming with whiskey, cola and eye-popping local Red Bull, for just a few dollars. Beach bars boasting floor-to-ceiling speakers blast out ear-shattering electronica until the early hours. Narcotics, violent crime and sexual assault are rife. Nevertheless, with the northern summer in full swing, even more young people from across North America and Europe will descend here, joined by young South Africans, Australians and New Zealanders escaping the southern winter. They risk at the very least their dignity, and at most their lives, to fulfill what is now a backpacker rite of passage.

The name “full-moon party” lends a vaguely pagan air to the proceedings, but in truth the gatherings were first held when the moon was at its biggest and brightest for practical reasons. In the 1980s, Koh Phangan was a rough and ready place after dark. Packs of feral dogs roamed, so did muggers. Shootings were a fact of life. However, the brilliant lunar illumination brought relative safety and a brief respite. It was “an evening of getting naked, splashing in the sea, and dancing around imaginary Stonehenges,” recalls Hinshelwood, whose memory of the event can be read at length here. At the inception of the full-moon parties, there was no electricity on Haad Rin — aging flower children complained of “colonialism” when it eventually arrived. The festivities centered on tents, campfires and music the partygoers made themselves. All this took place in the incomparable natural setting of the Gulf of Thailand, immortalized through Alex Garland’s novel The Beach and its big-screen adaptation starring Leonardo DiCaprio. Joe Cummings, whose Lonely Planet Guide to Thailand has sold countless copies since it first appeared in 1982, visited Haad Rin in 1983 and tells TIME that it was “one of the most beautiful beaches I’d ever seen.” When he next returned in 1989, the full-moon parties were still intimate affairs, attracting no more than 2,000 people.

These days, however, there can be little doubt of the toll the decades of debauchery have taken on the environment. In addition to the vast quantities of broken glass and plastic strewn across the sand each month, the island is currently in the throes of a freshwater crisis as it seeks to accommodate an unfeasibly large number of visitors. Hard drugs are now part of the scene — as opposed to the relatively benign marijuana and hallucinogenic mushrooms of yore — with ravers these days seeking out ya ba (the local name for crystal meth) as well as ecstasy and heroin. The difference in atmosphere is profound. Drownings have become an unsurprising annual occurrence, given the number of intoxicated revelers on a beach with no lifeguards on duty. Dozens are ferried to mainland hospitals with a litany of indulgence-induced ailments (often severe burns from inebriated bouts of fire dancing). Rapes are frequent and often unreported. Thai police have a well-documented corruption problem and many visitors get caught in stings arranged with local drug dealers, with steep “fines” demanded to secure their release. A nadir was reached last year, when British tourist Stephen Ashton was killed on New Year’s Eve. The 22-year-old was dancing with friends at a waterfront bar when a dispute between two local gangs escalated and someone fired into the crowd. Ashton was hit in the chest and could not be revived. Ekkapan Kaewkla, 26, pleaded guilty to manslaughter.

The Tourist Authority of Thailand has attempted to revamp the Koh Phangan’s image in recent times, and boutique resorts have opened on the more tranquil western and northern shores. A new airport is due to finally open in the fall, meaning the island will be only an hour away from Bangkok, putting it well within reach of the luxury-weekend crowd. It seems that “Koh Phangan’s days as a backpacker place are numbered,” says travel writer Andrew Bond, who has written about Thailand for a decade. In other words, as young people begin to arrive in Haad Rin for the next full-moon party on July 24, they will find an event that is not in any immediate danger of extinction, but one that has certainly passed its hedonistic peak. Considering what the full-moon parties used to be, and what they’ve become, that’s no bad thing.